A web page consists of markup—HTML (HyperText Markup Language) that describes the meaning of the content on the page—and CSS (Cascading Style Sheets) that tell the browser how the content should be displayed in browsers and other user agents that need to display it. CSS tells the browser everything from the layout of the page to the colors of your headings.
CSS3 is the latest version of the CSS specification. The term “CSS3” is not just a reference to the new features in CSS, but the third level in the progress of the CSS specification. CSS3 contains just about everything that’s included in CSS2.1 (the previous version of the specification). It also adds new features to help developers solve a number of problems without the need for non-semantic markup, complex scripting, or extra images.
Features that are included in CSS3 include support for additional selectors, drop shadows, rounded corners, multiple backgrounds, animation, transparency, and much more.
Why should I care about CSS3?
Some design techniques find their way into almost every project. Drop shadows, gradients, and rounded corners are three good examples. We see them everywhere. When used appropriately, and in harmony with a site’s overall theme and purpose, these enhancements can make a design flourish.
Perhaps you’re thinking: we’ve been creating these design elements using CSS for years now. But have we?
In the past, in order to create gradients, shadows, and rounded corners, web designers have had to resort to a number of tricky techniques. Sometimes extra HTML elements were required. In cases where the HTML is kept fairly clean, scripting hacks were required. In the case of gradients, the use of extra images was inevitable. We put up with these workarounds, because there was no other way of accomplishing those designs.
CSS3 allows you to include these and other design elements in a forward-thinking manner that leads to so many benefits: clean markup that is accessible to humans and machines, maintainable code, fewer extraneous images, and faster loading pages.
Time to get learning!
This is an excerpt from HTML5 & CSS3 for the Real World, by Alexis Goldstein, Louis Lazaris & Estelle Weyl.